Aerial imaging high-accuracy scale calibration

ABSTRACT

The disclosure provides for a system of markers and methods of using the system of markers to provide a precise scene scale reference for captured aerial images. Each of the markers may include one or more pairs of aligned collimated light emitters, where each pair of light emitters is configured to emit two light beams that converge at a known distance from the marker. When two or more markers are used, the system of markers may be aligned in a unique physical orientation to form a shape of known dimensions (e.g., a line, a triangle, or square) that provides an accurate scene scale reference for captured images.

BRIEF SUMMARY OF THE DISCLOSURE

The disclosure describes a system of markers and methods of using thesystem of markers to provide an accurate scene scale reference forcaptured aerial images.

In one example, a method includes: placing and aligning a plurality ofmarkers in a location such that a surface of each of the plurality ofmarkers is illuminated by a pair of intersecting collimated light beamsthat are emitted by a pair of light emitters of another one of theplurality of markers, where each of the pairs of light beams converge ata known distance from the marker that emits the pair of light beams;after placing and aligning the plurality of markers, capturing an aerialimage of the location, where the captured aerial image includes theplurality of placed and aligned markers; and using the known distanceand placed and aligned markers in the captured aerial image to create ascale for the image. In some implementations, the plurality of aerialimages may be captured using an unmanned aerial vehicle.

In particular implementations, the method may further include: afterplacing and aligning the plurality of markers, capturing a plurality ofaerial images of the location, wherein each of the plurality of capturedaerial images include the plurality of placed and aligned markers; andgenerating a three-dimensional model of the location using the pluralityof captured images, where objects in the three-dimensional model arescaled using the known distance and placed and aligned markers in theplurality of captured aerial images.

In some implementations, the plurality of markers comprise two markersplaced and aligned in a linear configuration. In some implementations,the plurality of markers comprise three markers placed and aligned in atriangular configuration, or four markers placed and aligned in arectangular configuration.

In some implementations, each of the pluralities of markers comprises afirst pair of light emitters that emit light beams that converge at afirst known distance from the marker in a first direction, and a secondpair of light emitters that emit light beams that converge at a secondknown distance from the marker in a second direction. To facilitateplacement and alignment, each of the markers may emit collimated lightin the visible light spectrum.

In some implementations, placing and aligning the plurality of markersincludes mounting each of the plurality of markers on a stand such thateach of the plurality of markers are level and vertically aligned witheach of the other plurality of markers.

In some implementations, a top surface of each of the plurality ofmarkers comprises a pattern, and the method further includes:determining a center of each of the plurality of markers in the capturedimage using at least the pattern.

In particular implementations, the known distance is greater than 10meters, greater than 20 meters, greater 30 meters, greater than 40meters, or even greater 50 meters.

In another example, a system includes: a first marker including a pairof light emitters that emit light beams that converge at a first knowndistance from the first marker; a second marker including a pair oflight emitters that emit light beams that converge at a second knowndistance from the second marker; and a non-transitory computer-readablemedium having machine-readable instructions stored thereon that whenexecuted: receive an aerial image of a location, the aerial imageincluding a plurality of markers; and using at least the first knowndistance, the second known distance, and the plurality of markers in theaerial image, create a scale for the image. In some implementations, thesystem may further include: a plurality of stands to level andvertically align the first and second markers.

In implementations, the first marker includes a first pair of lightemitters that emit light beams that converge at a first known distancefrom the first marker in a first direction, and a second pair of lightemitters that emit light beams that converge at a second known distancefrom the first marker in a second direction. Each of the light emittersof the first and second markers may emit collimated light in the visiblelight spectrum.

In implementations, execution of the instructions may further causes thesystem to: receive a plurality of aerial images of the location, each ofthe plurality of aerial images including the plurality of markers; andgenerate a three-dimensional model of the location using the pluralityof aerial images, where objects in the three-dimensional model arescaled using at least the first known distance, the second knowndistance, and the plurality of markers in the plurality of aerialimages.

In a further example, a marker includes: a power source to power aplurality of light emitters; a first pair of collimated light emitters,the first pair of collimated light emitters to emit visible light beamsthat converge at a known distance in a first direction; a second pair ofcollimated light emitters, the second pair of collimated light emittersto emit visible light beams that converge at a known distance in asecond direction, and an outer surface including a plurality of notches,where each of the collimated light emitters is to emit light through arespective one of the plurality of notches.

Other features and aspects of the disclosed method will become apparentfrom the following detailed description, taken in conjunction with theaccompanying drawings, which illustrate, by way of example, the featuresin accordance with embodiments of the disclosure. The summary is notintended to limit the scope of the claimed disclosure, which is definedsolely by the claims attached hereto.

It should be appreciated that all combinations of the foregoing concepts(provided such concepts are not mutually inconsistent) are contemplatedas being part of the inventive subject matter disclosed herein. Inparticular, all combinations of claimed subject matter appearing at theend of this disclosure are contemplated as being part of the inventivesubject matter disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure, in accordance with one or more implementations,is described in detail with reference to the following figures. Thefigures are provided for purposes of illustration only and merely depictexample implementations. Furthermore, it should be noted that forclarity and ease of illustration, the elements in the figures have notnecessarily been drawn to scale.

Some of the figures included herein illustrate various implementationsof the disclosed technology from different viewing angles. Although theaccompanying descriptive text may refer to such views as “top,” “bottom”or “side” views, such references are merely descriptive and do not implyor require that the disclosed technology be implemented or used in aparticular spatial orientation unless explicitly stated otherwise.

FIG. 1 illustrates an example environment in which the disclosure may beimplemented.

FIG. 2 is an operational flow diagram illustrating an example method forcreating a three-dimensional model of an outdoor location with accuratescaling using a system of markers, in accordance with implementations ofthe disclosure.

FIG. 3 is a block diagram illustrating a top view of an example marker,in accordance with implementations of the disclosure.

FIG. 4 illustrates an example internal design of an opened marker inalignment with another open marker, in accordance with implementationsof the disclosure.

FIG. 5 illustrates an example external design of an assembled marker, inaccordance with implementations of the disclosure.

FIG. 6 is an operational flow diagram illustrating an example methodthat may be performed to align a system of markers in outdoor locationpoints where marker light beam pairs converge, in accordance withimplementations of the disclosure.

FIG. 7 is a schematic diagram illustrating an example configuration of asystem of three identical disk-shaped markers that are aligned andpositioned in a location, in accordance with implementations of thedisclosure.

FIG. 8 illustrates an example computing module that may be used toimplement various features of the system and methods disclosed herein.

The figures are not exhaustive and do not limit the disclosure to theprecise form disclosed.

DETAILED DESCRIPTION

Although photo-based three-dimensional (3D) scans and aerial surveyshave begun to approach the detail level of Lidar data, there is as yetno reliably accurate method to scale data collected of large scenes suchas sets or locations. For example, tape measurements are unreliable whentaken of a large scale area. When the tape measurements are off by evena small fraction of the measured distances (e.g., a few percentilepoints), these errors are greatly amplified when used to determinedimensions of a large scale area (e.g., a city block, an open field, apark, or other large scene). This inaccurate scaling can be problematicwhen using aerial or other images to photogrammetrically createthree-dimensional models.

Another conventional method for scaling data is referencing a “known”object in aerial photographs. For example, the length of a car or otherknown object may provide a rough reference for determining scale.However, such conventional methods suffer greatly from cumulative errorand are unreliable for any accurate measurements that may entail asignificant cost where there is error.

Although large markers of known dimensions could also potentially beused to provide an accurate scaling reference in aerial images of largescenes, such markers would be impractical for general use. For example,it would not be practical for human operators to carry, transport, orstore physical markers having a diameter of over 10 meters to variousscene locations.

To this end, the disclosure describes a system of marker devices(“markers”) and methods of using the system of markers to provide anaccurate scene scale reference for captured aerial images. In accordancewith implementations, each of the markers may include one or more pairsof aligned light emitters (e.g., lasers or diodes), where each pair oflight emitters is configured to emit two light beams that intersect andconverge at a known distance from a point of the marker (e.g., thecenter of the marker). When two or more markers are used, the system ofmarkers may be aligned in a unique physical orientation to form a shapeof known dimensions (e.g., a line, a triangle, or square) that providesan accurate scene scale reference for captured images.

As will be appreciated from the foregoing disclosure, the describedsystem of markers allows for hand placement of the markers whilemaintaining a high level of accuracy. Additionally, the described systemof markers may provide for a relatively inexpensive and portablesolution to the problem of providing a marker in photographs of largescenes for precise scaling.

FIG. 1 illustrates an example environment 100 in which the disclosuremay be implemented. FIG. 1 will be described together with FIG. 2, whichis an operational flow diagram illustrating an example method 200 forcreating a three-dimensional model of an outdoor location with accuratescaling using a system of markers in accordance with implementations ofthe disclosure.

Prior to producing video or photographic content at an outdoor location150, the location may be scouted. For example, decisions as to whetherto shoot a movie or television series at a location may be made byindividuals called “scouts” who are sent to the site. A location scoutmay examine the environment, capture photographs (and possibly video) ofthe area, and send this information back to the production team.

To facilitate the scouting process, unmanned aerial vehicles (UAV) 140(e.g., quadcopter drones) may be equipped with a camera 145 (e.g., anomnidirectional camera) and remotely controlled by scouts to capture oneor more aerial images 155 of location 150. Utilizing an aerial unmannedvehicle in this context may facilitate traversal of outdoor location 150and may allow image capture from a variety of different angles. Forexample, a member of a video production team may remotely control UAV140 to capture images within a particular geographical location.Alternatively, UAV 140 may automatically scout and capture images oflocation 150 using a global positioning system (GPS) in combination withpredefined geographical coordinate boundaries for location 150 such aslatitude, longitude, and/or altitude. In other implementations, adigital single-lens reflex (DSLR) camera or other suitable camera may bemanually used by a scout to capture aerial images.

To provide a precise scene scale reference for captured aerial images oflocation 150, a system of two or more markers 170 may be placed inlocation 150 in accordance with implementations described. For example,the markers 170 may be placed by a human scout or by a machine. Asfurther described below, each of the markers 170 may include one or morepairs of aligned light emitters (e.g., lasers or diodes), where eachpair of light emitters is configured to emit two light beams thatconverge at a known or predetermined distance from a point of the marker(e.g., the center of the marker). For example, the light beams mayconverge at 25 meters, 50 meters, 75 meters, 100 meters, etc. When thetwo light beams converge, they may partially or completely overlap.

As such, at operation 210, the markers may be aligned in the outdoorlocation at location points where light beams emitted by the markerlight emitters converge. For example, each of the three markersillustrated in location 150 may be aligned and placed in a triangulararrangement such that a pair of light beams emitted by the other twomarkers converge at an edge, at the center, or some other point of themarker. Although a triangular arrangement is illustrated in the exampleof FIG. 1, in other implementations, the markers may be aligned andplaced in other arrangements depending on the number of markers and thescaling reference needs of the captured aerial images. For example, asystem of markers may be aligned in a line of two markers, multiplelines of two markers, a square of four markers, or some otherconfiguration.

In implementations, aligning the markers may also include leveling themarkers along a vertical dimension such that the markers have the sameheight (e.g., the same or substantially the same absolute altitude).This may be particularly advantageous in cases where the topography ofthe location is not mostly level (e.g., a location with several smallhills or where the ground slopes in one direction). Vertical alignmentmay be achieved by placing the markers on a stand and using tools suchas an altimeter, a cross-line laser leveler, or some other tool that maybe used to keep the markers 170 aligned along the vertical dimension.

As illustrated in the example of FIG. 1, the top surface of the body ofmarkers 170 is shaped as disks having a checkerboard pattern. In thisexample, the markers may be placed and aligned in location 150 such thatthe light emitters converge near or at a point on the outercircumference of the disks. In other implementations, the top surface ofthe body of markers 170 may have some other shape such as, for example,a rectangular shape, a star shape, or an irregular shape. The topsurface of the body of markers 170 may also comprise other patternsbesides a checkerboard pattern. In implementations, the shape and designof the top surface of markers 170 may be configured such that itprovides a recognizable reference for image recognition software toidentify the markers in an aerial image and/or determine the center ofthe markers for determining scaling distances.

Following alignment and placement of the markers, at operation 220, oneor more aerial images 155 of the outdoor location with the placedmarkers may be captured (e.g., using UAV 140). In implementations wheremultiple aerial images 155 are used to photogrammetrically create a 3Dmodel of the outdoor location, the number of captured images 155 maydepend on a minimum threshold needed to create a 3D model of the outdoorlocation, a desired accuracy of the 3D model, the size of the outdoorlocation, and specifications of camera 145 (e.g., field of view,resolution, dynamic range, etc.)

Following capture of images 155, UAV 140 may transmit the capturedimages 155 to one or more user devices 160 over communication network130 (e.g., a radio frequency network, a BLUETOOTH network, an infrarednetwork, a wired network, etc.). As illustrated, user device 160 is adesktop computer. However, the user device may include a smartphone, atablet, a laptop, a desktop computer, a server, a wearable device suchas a HMD, or other suitable device that may be used to create a 3D modelof the location where markers in the images are used to accurately scaleobject sizes in the models. Alternatively, UAV 140 may transmit images155 to an intermediary device that then transmits the images 155 to auser device that creates the 3D model of the location and/or simulatesthe lighting conditions of the location.

Following receipt of captured images 155, at operation 230, a userdevice 160 may use the captured images to generate a 3D model of theoutdoor location 150, where identified markers in the image and theknown convergence distances of the light beams emitted by the markersare used to scale object sizes in the model. The generated 3D model maybe a polygonal model, a curved model, a digitally sculpted model, orother suitable model. A variety of photogrammetric techniques may beused to generate the 3D model. In one implementation, two dimensionalimages may be aligned by finding common points and matching theirpositions. As more points are found and matched, the position at whicheach photo was taken can be determined, and a sparse point cloud can becreated. A dense point cloud can be generated by interpolating points onthe sparse point cloud, using the images to add more detail. The densepoint cloud can be converted into a wireframe model, and a surface canbe filled in on the wireframe model, creating a mesh. In a particularimplementation, a 3D model may be created by using a large-scalestructure-from-motion (SfM) algorithm that recovers a triangular mesh.

During generation of the 3D model, markers in the images may berecognized and used to create a scaling reference for the relative andabsolute sizes of objects. For example, a scale of the 3D model may bedetermined by dividing the known separation of the markers (e.g., basedon known convergence distance of light beams) by the model's measurementof the same points. By way of example, if it is known that the markersare separated by 10 meters, and the 3D model shows them as beingseparated by 3.5 meters, the 3D model may be scaled by a factor of10/3.5 to match the known value.

In implementations, the effectiveness of the 3D model for simulatinglighting of the actual location may be enhanced by texture mapping the3D model (e.g., adding color, surface texture, reflectivity,transparency, or other detail) to capture details such as concrete onbuildings, canvas on awnings, glass in windows, highly reflectivesurfaces, etc. One or more texture images having one or more dimensionsmay be applied to the 3D model.

Although in the example described above, markers 170 are used to providea scale reference in captured images for generating a 3D model, itshould be emphasized that the disclosure is not limited to thisapplication. For instance, it may be desirable to include markers 170 inan image to provide a scale reference for a single overhead 2D view of alocation.

FIG. 3 is a block diagram illustrating a top view of an example marker300 in accordance with implementations. Marker 300 may include a powersource 311, power circuitry 312, a power control 313, a first pair oflight emitters 314 a-314 b, and a second pair of light emitters 314c-314 d.

Power source 311 may be a battery such as a coin cell battery, aphotovoltaic cell battery or other suitable battery or power source thatpowers light emitters 314 a-314 d through power circuitry 312. Inalternative implementations, each light emitter may include its ownpower source, or combinations of light emitters may share respectivepower sources. A power control 313 may be implemented as a switch toturn power on or off (e.g., to turn the light emitters on/off). In someimplementations, power control 313 may include controls for turningon/off individual light emitters or pairs of light emitters.

Light emitters 314 a-314 d may be lasers, laser diodes, or some othertype of light emitter that may emit collimated light beams 315 a-315 dsuch that the light beam radius does not substantially increase over thedistances that markers 300 are separated. For example, at a distance of50 meters, the light beam may illuminate a surface of another markerwith a beam having a cross-sectional radius (e.g., a laser dot) of about1-2 centimeters. In implementations, the emitted light beams 315 a-315 dmay be in the visible color spectrum (e.g., red waveband or greenwaveband) to facilitate visual alignment and placement of the markerswith respect to the converging light beams. In some implementations, thelight beams of a pair of converging light beams may include light beamsin different colors in the color spectrum (e.g., red beam and green beamor red beam and blue beam) to facilitate visual alignment and placementof the markers. For example, a red laser dot and a green laser dot maybe projected on the surface of an illuminated surface, and these twodots may be centered to find the point of convergence.

In example marker 300, the light emitters are configured such that lightemitter pair 314 a-314 b emits light beams 315 a-315 b that converge ata predetermined or known distance from the marker along a firstdirection, and light emitter pair 314 c-314 d emits light beams 315c-315 d that converge at a predetermined or known distance from themarker along a second direction. In the example of FIG. 3, the first andsecond directions are orthogonal and have an angular displacement of 90degrees. In other implementations, the angular displacement may be 60degrees, 120 degrees, 180 degrees, or some other suitable displacementdepending on how the other markers are placed in the scene.

The predetermined distance of convergence of each light beam pair may be10 meters, 20 meters, 30 meters, 50 meters, 100 meters, or even greaterdepending on the scaling distances needed for one or more aerial imagesof a location. Additionally, the predetermined distance of convergenceof each light beam pair need not be the same. For example, light beams315 a-315 b may converge at 50 meters and beams 315 c-315 d may convergeat 100 meters. In some implementations, the predetermined distance ofconvergence may be fixed for a light emitter pair. In otherimplementations, the predetermined distance of convergence may beadjustable. For example, marker 300 may include one or more motors andactuators for rotating a pair of light emitters inward (i.e., towardeach other) to decrease the distance of convergence, or outward (i.e.,away from each other) to increase the distance of convergence. In theseimplementations, the distance of convergence may be adjusted in stepwiseincrements such as 1 meter, 2 meters, etc.

Although two pairs of light emitters are illustrated in the exampleimplementation of marker 300, in other implementations the marker mayinclude one pair of light emitters or more than two pairs of lightemitters. For instance, in environments where marker 300 is configuredto be aligned with only one other marker, only one pair of converginglight emitters may be needed.

Also illustrated in the example of FIG. 3 is a stand 310 on which marker300 may be mounted to vertically align with other markers (e.g., to havethe same absolute altitude). The stand may be a tripod having anadjustable height or other suitable platform that may be height adjustedand provides a surface for mounting marker 300. In implementations, thestand 310 may include a bubble level or other level device for levelingalong a horizontal plane. Stand 310 may also include or be mounted withan altimeter, a laser line leveler, or other suitable device forensuring that marker 300 is vertically aligned (e.g., at substantiallythe same absolute altitude) with other markers positioned at locationswhere light beams 315 a-315 b converge or where light beams 315 c-315 dconverge. The other markers may be similarly be positioned on heightadjustable stands. In some implementations, marker 300 and stand 310 maybe integrated into one device.

In implementations, marker 300 may be light weight and portably-sized tofacilitate placement in different scene locations during scouting of alocation. For example, marker 300 may be disk-shaped and have a diameterof less than 2 meters, less than 1 meter, or even less than 0.5 meters.

FIG. 4 illustrates an example internal design of an opened marker 400 inalignment with another open marker, in accordance with implementations.As illustrated, marker 400 is disk-shaped and includes a power source410, a first pair of light emitters 411-412 (e.g., lasers) that emitcollimated light beams that converge at a predetermined distance in afirst direction, and second pair of light emitters 413-414 (e.g.,lasers) that emit collimated light beams that converge at apredetermined distance in a second direction (e.g., at the location ofthe second marker). As also illustrated, each light emitter 411-414 ispositioned in a groove and light beams emitted by each light emitter areguided through a respective groove 421-424 to ensure and maintainprecise alignment of the system. When the marker 400 is fully assembled,the ends of each groove may provide an aperture or notch through whicheach light beam is guided.

In some implementations, the entrance of grooves 421-424 may alsoprovide an alignment point for aligning incoming converging light beamsfrom other markers. In other implementations, some other alignment pointon the surface of marker 400 may be used. For example, alignment pointsmay be centered or otherwise distributed between adjacent grooves.

FIG. 5 illustrates an example external design of an assembled marker 500in accordance with implementations. As illustrated, a top surface 510 ofmarker 500 includes a checkerboard pattern that may facilitateidentification of the center of marker 500 in an aerial image (e.g.,using imaging recognition software). In other implementations, the topsurface of marker 500 may include some other pattern (e.g., a bullseye)that facilitates identification of the center of marker 500. Assembledmarker 500 additionally includes notches 520 through which lightemitters emit light. As illustrated in this example, marker 500 hasthree notch pairs. In example marker 500, notches 520 may besymmetrically arranged around the disk such that the marker may be usedin different positions in a scene location.

FIG. 6 is an operational flow diagram illustrating an example method 600that may be performed to align a system of markers in outdoor locationpoints where marker light beam pairs converge. At operation 610, thelight emitters of the system of markers may be turned on. Light emittersmay be turned on before any markers are positioned, or light emittersmay be turned on as needed as markers are positioned. At operation, 620,the first marker may be positioned in the outdoor location. For example,the first marker may be leveled on a stand and positioned to emit lightbeams that converge in one or more directions at known distances. Atoperation 630, a second marker may be positioned in the outdoor locationat a convergence point of a light beam pair of the first marker and suchthat a light beam pair of the second marker converges at the firstmarker. By way of example, a marker 500 may be positioned such thatvisible laser dot pairs substantially overlap and are projected betweenadjacent grooves 520 on a surface of marker 500 or some other locationon a surface of marker 500. During positioning, marker 500 may beleveled on a stand such that it is in vertical alignment with the othermarker. Additionally, marker 500 may be positioned such that itsimilarly illuminates another marker having the same configuration.

If there are additional markers in the system of markers (decision 640),at operation 650 the additional marker may be similarly positioned suchthat they are illuminated by converging light beam pairs from one ormore of the other markers and such that they similarly illuminate one ormore of the other markers. Operation 650 may be iterated until allmarkers are positioned.

FIG. 7 is a schematic diagram illustrating an example configuration of asystem of three identical disk-shaped markers 710 that are aligned andpositioned in a location. As illustrated, the three markers 710 arepositioned in a triangular configuration where each dimension of thetriangle has a known distance based on a known convergence distance froma center of a marker and/or known dimensions of the markers.

FIG. 8 illustrates an example computing component that may be used toimplement various features of the system and methods disclosed herein,such as the aforementioned features and functionality of one or moreaspects of location simulation device 160.

As used herein, the term module might describe a given unit offunctionality that can be performed in accordance with one or moreembodiments of the present application. As used herein, a module mightbe implemented utilizing any form of hardware, software, or acombination thereof. For example, one or more processors, controllers,ASICs, PLAs, PALs, CPLDs, FPGAs, logical components, software routinesor other mechanisms might be implemented to make up a module. Inimplementation, the various modules described herein might beimplemented as discrete modules or the functions and features describedcan be shared in part or in total among one or more modules. In otherwords, as would be apparent to one of ordinary skill in the art afterreading this description, the various features and functionalitydescribed herein may be implemented in any given application and can beimplemented in one or more separate or shared modules in variouscombinations and permutations. Even though various features or elementsof functionality may be individually described or claimed as separatemodules, one of ordinary skill in the art will understand that thesefeatures and functionality can be shared among one or more commonsoftware and hardware elements, and such description shall not requireor imply that separate hardware or software components are used toimplement such features or functionality.

Where components or modules of the application are implemented in wholeor in part using software, in one embodiment, these software elementscan be implemented to operate with a computing or processing modulecapable of carrying out the functionality described with respectthereto. One such example computing module is shown in FIG. 8. Variousembodiments are described in terms of this example-computing module 800.After reading this description, it will become apparent to a personskilled in the relevant art how to implement the application using othercomputing modules or architectures.

Referring now to FIG. 8, computing module 800 may represent, forexample, computing or processing capabilities found within desktop,laptop, notebook, and tablet computers; hand-held computing devices(tablets, PDA's, smart phones, cell phones, palmtops, etc.); mainframes,supercomputers, workstations or servers; or any other type ofspecial-purpose or general-purpose computing devices as may be desirableor appropriate for a given application or environment. Computing module800 might also represent computing capabilities embedded within orotherwise available to a given device. For example, a computing modulemight be found in other electronic devices such as, for example, digitalcameras, navigation systems, cellular telephones, portable computingdevices, modems, routers, WAPs, terminals and other electronic devicesthat might include some form of processing capability.

Computing module 800 might include, for example, one or more processors,controllers, control modules, or other processing devices, such as aprocessor 804. Processor 804 might be implemented using ageneral-purpose or special-purpose processing engine such as, forexample, a microprocessor, controller, or other control logic. In theillustrated example, processor 804 is connected to a bus 802, althoughany communication medium can be used to facilitate interaction withother components of computing module 800 or to communicate externally.

Computing module 800 might also include one or more memory modules,simply referred to herein as main memory 808. For example, preferablyrandom access memory (RAM) or other dynamic memory, might be used forstoring information and instructions to be executed by processor 804.Main memory 808 might also be used for storing temporary variables orother intermediate information during execution of instructions to beexecuted by processor 804. Computing module 800 might likewise include aread only memory (“ROM”) or other static storage device coupled to bus802 for storing static information and instructions for processor 804.

The computing module 800 might also include one or more various forms ofinformation storage mechanism 810, which might include, for example, amedia drive 812 and a storage unit interface 820. The media drive 812might include a drive or other mechanism to support fixed or removablestorage media 814. For example, a hard disk drive, a solid state drive,a magnetic tape drive, an optical disk drive, a CD or DVD drive (R orRW), or other removable or fixed media drive might be provided.Accordingly, storage media 814 might include, for example, a hard disk,a solid state drive, magnetic tape, cartridge, optical disk, a CD, DVD,or Blu-ray, or other fixed or removable medium that is read by, writtento or accessed by media drive 812. As these examples illustrate, thestorage media 814 can include a computer usable storage medium havingstored therein computer software or data.

In alternative embodiments, information storage mechanism 810 mightinclude other similar instrumentalities for allowing computer programsor other instructions or data to be loaded into computing module 800.Such instrumentalities might include, for example, a fixed or removablestorage unit 822 and an interface 820. Examples of such storage units822 and interfaces 820 can include a program cartridge and cartridgeinterface, a removable memory (for example, a flash memory or otherremovable memory module) and memory slot, a PCMCIA slot and card, andother fixed or removable storage units 822 and interfaces 820 that allowsoftware and data to be transferred from the storage unit 822 tocomputing module 800.

Computing module 800 might also include a communications interface 824.Communications interface 824 might be used to allow software and data tobe transferred between computing module 800 and external devices.Examples of communications interface 824 might include a modem orsoftmodem, a network interface (such as an Ethernet, network interfacecard, WiMedia, IEEE 802.XX or other interface), a communications port(such as for example, a USB port, IR port, RS232 port Bluetooth®interface, or other port), or other communications interface. Softwareand data transferred via communications interface 824 might typically becarried on signals, which can be electronic, electromagnetic (whichincludes optical) or other signals capable of being exchanged by a givencommunications interface 824. These signals might be provided tocommunications interface 824 via a channel 828. This channel 828 mightcarry signals and might be implemented using a wired or wirelesscommunication medium. Some examples of a channel might include a phoneline, a cellular link, an RF link, an optical link, a network interface,a local or wide area network, and other wired or wireless communicationschannels.

In this document, the terms “computer readable medium”, “computer usablemedium” and “computer program medium” are used to generally refer tonon-transitory media, volatile or non-volatile, such as, for example,memory 808, storage unit 822, and media 814. These and other variousforms of computer program media or computer usable media may be involvedin carrying one or more sequences of one or more instructions to aprocessing device for execution. Such instructions embodied on themedium, are generally referred to as “computer program code” or a“computer program product” (which may be grouped in the form of computerprograms or other groupings). When executed, such instructions mightenable the computing module 800 to perform features or functions of thepresent application as discussed herein.

Although described above in terms of various exemplary embodiments andimplementations, it should be understood that the various features,aspects and functionality described in one or more of the individualembodiments are not limited in their applicability to the particularembodiment with which they are described, but instead can be applied,alone or in various combinations, to one or more of the otherembodiments of the application, whether or not such embodiments aredescribed and whether or not such features are presented as being a partof a described embodiment. Thus, the breadth and scope of the presentapplication should not be limited by any of the above-describedexemplary embodiments.

Terms and phrases used in this document, and variations thereof, unlessotherwise expressly stated, should be construed as open ended as opposedto limiting. As examples of the foregoing: the term “including” shouldbe read as meaning “including, without limitation” or the like; the term“example” is used to provide exemplary instances of the item indiscussion, not an exhaustive or limiting list thereof; the terms “a” or“an” should be read as meaning “at least one,” “one or more” or thelike; and adjectives such as “conventional,” “traditional,” “normal,”“standard,” “known” and terms of similar meaning should not be construedas limiting the item described to a given time period or to an itemavailable as of a given time, but instead should be read to encompassconventional, traditional, normal, or standard technologies that may beavailable or known now or at any time in the future. Likewise, wherethis document refers to technologies that would be apparent or known toone of ordinary skill in the art, such technologies encompass thoseapparent or known to the skilled artisan now or at any time in thefuture.

The presence of broadening words and phrases such as “one or more,” “atleast,” “but not limited to” or other like phrases in some instancesshall not be read to mean that the narrower case is intended or requiredin instances where such broadening phrases may be absent. The use of theterm “module” does not imply that the components or functionalitydescribed or claimed as part of the module are all configured in acommon package. Indeed, any or all of the various components of amodule, whether control logic or other components, can be combined in asingle package or separately maintained and can further be distributedin multiple groupings or packages or across multiple locations.

Additionally, the various embodiments set forth herein are described interms of exemplary block diagrams, flow charts and other illustrations.As will become apparent to one of ordinary skill in the art afterreading this document, the illustrated embodiments and their variousalternatives can be implemented without confinement to the illustratedexamples. For example, block diagrams and their accompanying descriptionshould not be construed as mandating a particular architecture orconfiguration.

While various embodiments of the present disclosure have been describedabove, it should be understood that they have been presented by way ofexample only, and not of limitation. Likewise, the various diagrams maydepict an example architectural or other configuration for thedisclosure, which is done to aid in understanding the features andfunctionality that can be included in the disclosure. The disclosure isnot restricted to the illustrated example architectures orconfigurations, but the desired features can be implemented using avariety of alternative architectures and configurations. Indeed, it willbe apparent to one of skill in the art how alternative functional,logical or physical partitioning and configurations can be implementedto implement the desired features of the present disclosure. Also, amultitude of different constituent module names other than thosedepicted herein can be applied to the various partitions. Additionally,with regard to flow diagrams, operational descriptions and methodclaims, the order in which the steps are presented herein shall notmandate that various embodiments be implemented to perform the recitedfunctionality in the same order unless the context dictates otherwise.

What is claimed is:
 1. A method, comprising: aligning a plurality ofphysical markers arranged at separate positions from one another in anoutdoor location such that a surface of each of the plurality ofphysical markers is illuminated by a pair of intersecting collimatedlight beams emitted by a pair of light emitting devices of another oneof the plurality of physical markers, wherein each of the pairs of lightbeams converge at a known distance that is at least 10 meters from thephysical marker that emits the pair of light beams; capturing by anaerial vehicle flying over the outdoor location, a plurality of aerialimages of the outdoor location, wherein the plurality of captured aerialimages are captured at different positions over the outdoor location andinclude a representation of the plurality of aligned physical markers inthe outdoor location; analyzing the plurality of captured aerial images,the known distance of the convergence of the pairs of light beams, andthe aligned physical markers to create a scale for the aerial image; andgenerating a three-dimensional model of the outdoor location using theplurality of captured images, wherein objects in the three-dimensionalmodel are scaled using the known distance of the convergence of pairs oflight beams and the aligned physical markers in the plurality ofcaptured images.
 2. The method of claim 1, wherein the plurality ofphysical markers comprise two physical markers positioned at a firstposition in the outdoor location and a second position in the outdoorlocation, respectively, and aligned in a linear configuration.
 3. Themethod of claim 1, wherein the plurality of physical markers comprisethree physical markers positioned at three different positions in theoutdoor location and aligned in a triangular configuration, or fourphysical markers positioned at four different positions in the outdoorlocation and aligned in a rectangular configuration.
 4. The method ofclaim 1, wherein each of the plurality of physical markers comprises afirst pair of light emitting devices that emit light beams that convergeat a first known distance from the physical marker in a first direction,and a second pair of light emitting devices that emit light beams thatconverge at a second known distance from the physical marker in a seconddirection.
 5. The method of claim 4, wherein each of the light emittingdevices of each of the plurality of physical markers emits light havinga wavelength in the visible light spectrum.
 6. The method of claim 1,wherein aligning the plurality of physical markers comprises mountingeach of the plurality of physical markers on a stand such that each ofthe plurality of physical markers is level and vertically aligned witheach of the other physical markers.
 7. The method of claim 1, wherein atop surface of each of the plurality of physical markers comprises apattern, wherein the method further comprises: determining a center ofeach of the plurality of physical markers in at least one of theplurality of captured aerial images using at least the pattern.
 8. Themethod of claim 4, wherein each of the first known distance and thesecond known distance is greater than 10 meters.
 9. The method of claim8, wherein each of the first known distance and the second knowndistance is greater than 50 meters.